[ARROW-15479] [C++] Cast fixed size list to compatible fixed size list type (other values type, other field name)

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 10.0.0
• Component/s: C++
• Labels: good-second-issue kernel pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/30955
• Assignee: Kshiteej K
• Reporter: Joris Van den Bossche
• Created: 27/Jan/22 15:12
• Updated: 11/Jan/23 11:37
• Resolved: 28/Sep/22 22:16

Description

Casting a FixedSizeListArray to a compatible type but only a different field name isn't implemented:

>>> my_type = pa.list_(pa.field("element", pa.int64()), 2)
>>> arr = pa.FixedSizeListArray.from_arrays(pa.array([1, 2, 3, 4, 5, 6]), 2)
>>> arr.type
FixedSizeListType(fixed_size_list<item: int64>[2])
>>> my_type
FixedSizeListType(fixed_size_list<element: int64>[2])

>>> arr.cast(my_type)
...
ArrowNotImplementedError: Unsupported cast from fixed_size_list<item: int64>[2] to fixed_size_list using function cast_fixed_size_list

While the similar operation with a variable sized list actually works:

>>> my_type = pa.list_(pa.field("element", pa.int64()))
>>> arr = pa.array([[1, 2], [3, 4]], pa.list_(pa.int64()))
>>> arr.type
ListType(list<item: int64>)
>>> arr.cast(my_type).type
ListType(list<element: int64>)

Issue Links

• links to: GitHub Pull Request #14181